This invention relates to an endoscopic manipulating wire coupling structure.
Endoscopic manipulating wires are generally composed of two or more fine twisted metal stands so that they will not get prone to bend easily. An end of such endoscopic manipulating wire is inserted into an opening in a mating member and securely coupled to the latter by a suitable means such as brazing with sliver or soldering.
In the case of brazing with silver, the areas to be coupled of the two members need be heated up to about 600xc2x0 C. To meet this need, a small burner is typically used as the heater but because of the heat capacity of the portions being heated, that part of the manipulating wire which is not inserted into the mating member is prone to become hotter than the other part which is inserted into the mating member.
This prevents the brazing silver from reaching every part of the areas that need be securely coupled. On the other hand, the silver flows out to the adjacent area of the manipulating wire which is not inserted into the mating member and the length of the rigid portion exceeds a design value or the manipulating wire may be oxidized to present a problem with strength.
In the case of soldering, the strength it can achieve is inherently low and if any of the flux used in the soldering operation remains unremoved, the strength it presents will decrease at a later time to increase the chance of discoupling between the manipulating wire and the mating member. To avoid this problem, the flux must be washed away from the coupled parts to but this is very cumbersome to achieve.
As an alternative method, an end of the manipulating wire may be inserted into an opening in the mating member which is then clamped to deform plastically from the outer circumference inward so that it is securely pressed against the manipulating wire.
If this method is simply applied, the force exerted to cause plastic deformation of the mating member 60 is also transmitted to the inwardly positioned manipulating wire 50 as indicated in FIG. 14, so that the individual strands 51 collapse to a smaller diameter and the resulting drop in strength increases the chance of wire breakage during service.
An object, therefore, of the present invention is to provide an endoscopic manipulating wire coupling structure by which a manipulating wire and a mating member can be securely coupled by a simple and positive operation while assuring consistent strength.
According to the invention, at least that portion of a mating member which is fitted over a manipulating wire is formed of a material softer than the manipulating wire, and deformed plastically from the outer circumference inward so that it is pressed to be securely coupled to the manipulating wire. Since this can be achieved without plastic deformation of the individual strands in the manipulating wire, the two members can be securely coupled together by a simple and positive operation while assuring consistent strength without reducing the diameter of the individual strands in the manipulating wire.
An endoscopic manipulating wire coupling structure of a preferred embodiment is generally constructed such that an end of a manipulating wire consisting of two or more twisted strands is inserted into an opening in a mating member which is plastically deformed from the outer circumference inward so that it is securely pressed against the manipulating wire. In the structure, at least that portion of the mating member which is fitted over the manipulating wire is formed of a material softer than the manipulating wire.
The mating member may be securely pressed against the manipulating wire at a plurality of sites spaced apart along the longitudinal axis. If desired, a tubular member formed of a material softer than the manipulating wire may be placed between the inner surface of the opening in the mating member and the manipulating wire inserted into the opening.
The manipulating wire may be used in an endoscopic treatment tool. Alternatively, it may be a curving manipulating wire in an endoscope.
The present disclosure relates to the subject matter contained in Japanese patent application No. Hei. 11-342735 (filed on Dec. 2, 1999), which is expressly incorporated herein by reference in its entirety.